Our long-term objective is the characterization of Ca 2 ion metabolism in normal and neoplastic cells. To attain this objective we propose (1) a detailed quantitative description of Ca 2 ion binding and uptake by normal and GD 248 leukemic hamster lymphocytes; (2) a qualitative description of Ca 2 ion -membrane interaction; and (3) a study of the effect of Ca2 ion on different metabolic functions of these cells and on membrane structure. A quantitative analysis of Ca 2 ion uptake by the cells will be achieved with standard Millipore-filtration methods. The qualitative details will be obtained in experiments with purified membrane fractions and intact cells employing fluorescent-lanthanides as Ca 2 ion probes and enzyme probes such as neuraminadase, phosphatidylserine decarboxylase. We will examine the functional role of Ca 2 ion in the regulation of glycolysis and respiration using standard biochemical techniques. The effect of Ca 2 ion on membrane structure will be analyzed with hydraulic and lipophilic photoactivated cross-linkers in conjunction with SDS-polyacrylamide electrophoresis to evaluate changes in protein-protein neighbor relationships. Ca 2 ion induced phase transitions in membrane proteins and lipids will be monitored by Raman spectroscopy. To relate the cell biology results obtained with intact cells with the biochemical characterization obtained with isolated membrane fractions we will employ the cyanine dye fluorescence method to monitor the membrane potential of intact cells, mitochondria and sealed plasma membrane vesicles under different physiological conditions, e.g., Ca 2 ion concentration, pH.